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What makes polystyrene so different from styrene? It’s a matter of chemistry

On April 22, 2016, the California Office of Environmental Health Hazard Assessment (OEHHA) listed the substance styrene on California’s Proposition 65 list, pursuant to the Safe Drinking Water and Toxic Enforcement Act of 1986 that requires the state to publish a list of substances known to cause cancer or birth defects or other reproductive harm.

There should be no confusion between styrene and polystyrene; they are two different materials. Although the names sound similar and may be confusing, styrene and polystyrene are different and have different properties.

Styrene is a liquid and is used in the manufacture of many materials in several applications like high-performance plastics, car tires, carpet backing, and reinforced fiberglass composites such as those used in bathtubs, automobile body panels, and wind turbines – and polystyrene. Polystyrene is used to make a variety of important consumer products, such as foodservice containers, cushioning for shipping delicate electronics, and insulation. Once these products are manufactured, they are inert.

The food safety benefits of plastic foodservice packaging including polystyrene are undisputed. At the same time, the plastics used in contact with food are carefully regulated. In the United States, the Food and Drug Administration regulates the safety of food contact packaging and has approved the use of polystyrene since 1958, as have other governments around the world. The National Toxicology Program (NTP) agrees that the safety of polystyrene in foodservice is not in question – pointedly saying that the safety of styrene is “not an issue.”

And, styrene’s listing under Prop 65 doesn’t change the decades of research that demonstrate polystyrene’s safe use in foodservice packaging.

For more information on the benefits and safety of polystyrene, click here.

Two different chemistries
Polystyrene

The Basics: When styrene molecules become linked together into a polymer, polystyrene is created. Polystyrene is an inert plastic that can be used to make many products, such as polystyrene foam used to make disposable plates, cups, and other foodservice packaging products.

How It’s Used: Polystyrene is used in many applications. One application is foodservice – polystyrene foam is a clean and affordable option to insulate food and to keep it fresher for a longer period of time. Polystyrene foam is a lightweight material, about 95% air, with very good insulation properties and is used in many types of products, such as cups that keep your beverages hot or cold. Polystyrene foam is also widely used in cushioning or protective packaging that helps keeps computers and appliances safe during shipping. Most people incorrectly use the name STYROFOAM® to refer to polystyrene; STYROFOAM® is a registered trademark of The Dow Chemical Company that refers to its branded building material products.

Styrene

The Basics: Styrene is a clear, colorless liquid that is a component of materials used to make thousands of everyday products. Styrene occurs naturally in many foods, such as cinnamon, beef, coffee beans, peanuts, wheat, oats, strawberries and peaches. Synthetic styrene, which is chemically identical to naturally occurring styrene, is manufactured as a chemical building block for materials used to make packaging, insulation, automobiles, electronics, boats, and recreational vehicles.

How It’s Used: For more than 70 years, styrene has been used a chemical building block used to manufacture many familiar products, such as food containers, rubber tires, building insulation, carpet backing and reinforced fiberglass composites such as boat hulls, surfboards, residential kitchen countertops, bathtubs and shower enclosures.

This post is an updated version of a July 2014 post on the same topic.

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